-PM-

iTrader: (2)

Ok, I finally had some time to mess around with the car again. Disconnected the TPS completely....same thing. 1/4 throttle would rev up fine....but if I press any harder, boost gauge jumps up a little and the car loses RPM's and dies.
Plugged in a working TPS, adjusted it to 1000 ohms, same problem.
Will be doing a fuel pressure test next....
Thinking clogged injectors at this point.....maybe?

-PM-

iTrader: (2)

Will also be doing the bypass as well. I'll post back with results.

-PM-

iTrader: (2)

Fuel pressure results:

key on, engine off: ~40psi
key on, engine idle: ~30psi
trying to rev the engine as much as I can: drops to ~25psi


Any thoughts?

bumpstart

fuel pump or the power feed to it is crapped
- new filter, new pump, new relay

-PM-

iTrader: (2)

Is that low?? I thought 30-40psi is normal...?

-PM-

iTrader: (2)

pump is brand new by the way....less than 50 miles on it

bumpstart

25 psi is too low
if you go WOT fuel pressure should go UP to the static set pressure
- whatever that is
( expecting 38-42 , depends on the fuel rail type and the fuel pump and if using the OEM 2 speed relay )

jump the fuel pump to run and disconnect the vacuum nipple from FPR to find out what that static pressure is on your car

the fuel pressure is lowest at idle ( high vacuum )
again,,depending on the model and fuel rail setup and the idle vacuum
this may be as low as 30 on some models and 38 at others ( at idle )
EG a car with a walbro and a full relay rewire and s4 rails may well make 42 psi static
and idles at 18 inch hg ( approx -9 psi ) would see 33 psi at idle

a bridge on the same fuel setup would idle at 10 inch Hg and thus be 42 static and 38 ish psi at idle

conversly,, a s5 with OEM pump and OEM pump control relay may well only be 38 psi static , and idle at 30 psig if stock ports

as such i would consider 30 psi at the extreme low end of acceptable at idle - bare in mind variances in guages

it should never dip lower than this idle value ( except in extreme decel )
and if it does, indicates a problem with flow through the pump and filter

rewire the pump for a 30 amp fused, disode protected relay and feed it from the battery

Kstout24

iTrader: (1)

My 91 NA has this exact problem. Read the whole first page and can't continue to the next ones for some reason on my phone. If the solution to this issue has been resolved please pm me with the answer.

satch

iTrader: (1)

Can your car rev properly when in neutral?

-PM-

iTrader: (2)

Should I do as Satch recommended and disconnect the plug for the pump relay and jump one of the blue wires to one of the blue/red ones to see if that helps?

Kstout24

iTrader: (1)

Nope, bogs down

satch

iTrader: (1)

You might want to look over the wiring related to the fuel circuit.

The possibility of clogged primary injectors.

Measuring the fuel pressure and see if the FPR, Pulsation Damper are working properly.

Condition of fuel filter, fuel pump and fuel sock.

-PM-

iTrader: (2)

Satch, do you agree with what Bumpstart says about the fuel pump?

satch

iTrader: (1)

His knowledge of these cars far surpasses mine so his input would be the the one to focus on.

bumpstart

it wont help if the issue is with the wiring and joins back to the pump
i consider all FC's as very suspect in this area
last time i bothered with the DMM on one of these it was 2 and 9 V in either state, showing issue with the old loom and not just at the 2 speed relay
( NB s4 NA cars lack the two speed circuit )

and as such the existing two speed circuit is good only as a signal to swing a new relay which takes feed from the battery or from a B+ bus point
especially when you fit a new pump
you may also need to add an earth strap to the lid of the pump to the body on some pumps

if you read post 200 , there is another happy camper in the rewire camp, a rewire is mandatory if you upgrade the pump

thats probs stretching it a bit , your knowledge of the US ecu and wiring is second to none
mines more rounded having been dulled by playing with JDM examples in various states of butchery
and mostly with dealing with aftermarket ecus and installs into oldschools
i do know that 25 psi is too low , OEM and not

HAILERS2

About your pressure results (fuel).

39psi is normal with key ON engine OFF (jumpering the fuel pump check connector to do so)

28-30 psi is normal on a idling car.

The part that is in question is your drop to 25 psi. IF you just sit there in the driveway and rev the engine your going to see a jump from the 30 psi at idle to perhaps 39-40 psi when the throttle is wide open...........but when you let off the pedal and the revs drop.......expect to see a figure lower than 30 psi since there is a lot of vacuum for a moment or so til you reach idle again.

Now IF you were driving the car and stomped on the pedal ....and got in BOOST.......the pressure whould rise above 39-40 psia nd climb to ??? depends....as much as 50 psi if in meaningful boost i.e. 10psi or so.

So the question is...........when you see 25 psi when reving, is that in the driveway??????? Need to clear that up a bit for us.

Personally I'd tie the fuel pressure gauge to the windshield wipers and go for a ride in boost and see the results. And or get a meter and long leads and read the fuel pump voltage by backprobing into the fuel pump connector back there. Should see 13 or so vdc when in boost.....less just plodding along.

-PM-

iTrader: (2)

That was in the driveway with me watching the gauge under the hood and trying to rev it via throttle cable.

I can't boost whatsoever. As soon as the car sees any boost (i.e. if I press the pedal down farther than 1/4 throttle), it bogs, jerks around, and dies. Even if I'm sitting in the drive way and mash the pedal all the way down, it jerks, bogs, and dies. I can only very lightly press the accelerator in order for it to rev up at least somewhat. Driving it and getting it over 20-30mph is nearly impossible (since I can't press the accelerator more than 1/4 way down).

Pump is new but not upgraded...just a new NAPA pump.

-PM-

iTrader: (2)

Update:

Did the fuel pump rewire. Same problem. Starts and idles but if I press down on the accelerator (more than 1/4 down), it bogs, jerks, and dies.
But now that I can hear the relay in the back, I've noticed something: When the ignition is on, the relay clicks, then the car starts. Then if I try flooring it, sometimes it clicks, sometimes it doesn't. It still won't rev up either way, but it's just something I've noticed.

Any thoughts? Maybe the relay/resistor is shot? Is there a way to bypass it completely and see if it will work fine without it?

bumpstart

sounds like the switch for the pump in the afm may be dicky ,, there is a fuel set connector to run the pump without the safety circuit

gear_grinder

iTrader: (4)

because mitsubishi made most of the wiring, i think... (take a look at DSMs and 3kgts, garbage)

-PM-

iTrader: (2)

How can I run the pump without the safety circuit to check if thats the case?

lastphaseofthis

iTrader: (8)

on the passanger side strut bar tower next to the turbo theres a 2 pin connector bridge that connector with a wire, and the fuel pump will run always with the key on.

have you pressurized the intake to make sure you dont have a leak in the system? i had a car bog when going in to boost, but otherwise ran fine, the primary injector wasn't seated correctly and boost was throwing the fuel back out around that injector...

-PM-

iTrader: (2)

I'll give that a try. Is it a specific color connector?
I haven't pressurized the intake system yet. What's the best way of doing that?

-PM-

iTrader: (2)

??

lastphaseofthis

iTrader: (8)

yellow. but i've seen a few fade to almost white.

i use a 2 inch PVC end cap drilled and tapped for threads to a air pressure regulator (with GAUGE!) i wouldn't go over 10 psi. although i have had systems hold find to 30.. maybe even more but i didn't want to push it.